Method of treatment of glass fibers with colloidal silica and product produced thereby



United States Patent Oflice 2,754,224 Patented July 10, 1956 METHOD OF TREA'I'MENT OF GLASS WTIH COLLOIDAL SHJICA AND PRODUCT PRODUCED THEREBY No Drawing: Application January'31, 1952,-

Serial No. 269,349

21 Claims. ((31; 117 -65) This'invention relates to the'production ofnew" glass fiber'products and'to'methods for producing'ithe. same;

This application is. a continuation-impart of my Co'- pending application S'er.'No: 101,495, filedbrr'June-ZS; 1949, and now abandoned.

In many ways, glass fibers constitute anideal material for textile fabrics, such as are usedt'in dress goods; draperies, curtains; insulations and the like, or as a fibrous basein coated fabrics and reinforced plastics. Yet, full utilization of'glass fibers for such purposes has suffered fora number of reasons, some of which have to do with characteristics or properties developed incident to other desirable treatments of the glass fibers.

For instance, upon attenuation, glass fibers form naturally into fine rod-like filaments having perfectly smooth and slippery surfaces. The low surface coefficient of friction permits the glass'fibers to moverelative to each other on the slightest provocation. As a result, glass fiber fabrics often fray quite badly and special precautions are required to prevent seams and-sewn edges from pulling out.

Hand and draping qualities in glass fibers and'fab'rics formed therefrom suffer from the slippage of the yarns caused by the smooth glass surfaces, and-this tendency to slippage militates against the use of glass yarns for some light weight fabrics, such as marquisettes, and the slippage is often detrimental even in heavier fabrics.

The smooth, non-porous surfaces of glass fibers provide little anchorage for coating or coloring compositions. This also tends to limit the use of the fabrics since both color and design constitute essential characteristics for textile materials. Those that might be coated orcolored through the medium of a resinous base or. the like, are subject to color diminution. More important the coating. is often easily removed under high humidity conditions, because the hydrophylic characteristics that predominate on. the glass fiber surfaces preferentially attractwater and under high humidity conditions, an intervening moisture layer may be induced which relaxes the bond between the coatingandthe glass fiber surfaces;

It has been found that the slippage and colorability of glass fibers may be markedly improved by thetreatment which includes the application of finely divided silica to the glass fiber surfaces, followed by a heat treatment, which. is instrumental in the development of a proper bond between the silica with the glass fiber surfacesin a manner which resists removal or separation from the glass fiber surfaces, as'an'incidence to normal handling;

The silica treatment operates not only to delusterthe fiber to a desired degree and to reduce the slippageofthe fibers in the fabric, but permanent coloring of glass fibers and fabrics can be achieved by conventional means. Thus the product formed therefrom is delustered color= able glass fiber having a coefficient of-friction' such that undesirable slippage between fibers does'not take place. A fabric prepared in accordance with this'inventionwill be characterized by softness; draping, and hand qualities ofth'e'finest silks; it will be wrinkle and crease-resistant;

it"mayjbe given. a permanent color or design; its luster mayjbe regylated'to meet the needs for a particular ap.- plication;rand.weave slippage is also reducedto permit the 'use ofglass fibers in light weight textile fabrics.

Byway of illustration, but not of limitation, the followingdefines armethod for carrying out this invention.

Example ]'.A fabric woven'of continuous-typeglass fibers is submerged in an aqueous suspension containing about'.15-per centcolloidal silica (SiOz). The treated fabric, thefibers of which are substantially completely coatedwith the silica composition, is driedand then it is subjectedfi to heat treatment at a temperature of. 105.0."- 1250 F. for two to three seconds, but may beexposedfor as long;.as thirty, minutes. At this temperature range, the organic substances, usually, appliedas. a size to,.the.ate tenuated'glass fibers, are almost immediately burned. or distilled off T6 prevent carbonization, which: deposits discoloring substances that arethereafter. difficult to re.- move from the glass fiber surfaces, it is desirable to. carry out heat treatment under oxidizing conditions. Suchconditionsare indic'atd'b'y burning-off. with a bluish flame andit may be.maintaii1ed by permitting. free. flow of air toth'e burningfzone or by. the injection. of oxygen-.01: oxygen-enrichedgasses- At th'is.-temperature, it also.ap pearsathatlthemoisture layer invariably present on. the glass fiber surfaces,.is substantially, eliminated.

Thus by the, elimination of size and by the conjoint layer. from the. glass fiber sur faces, bone.- dry conditions existwhich favor. intimate:as-. particles with the siliceous. materials of theglass fiber composition. T hissuggests the possible formationof entirely. new. reaction products on the glass fiber. surfaces-from which .the desirablemharacteristics .are derived- I'hismightexplain the ability, on. the orthand, ofeasily removingsilieadust heretofore applied asade-v lustrant to the glass-fiber surfaces; as comparedtothe relative inability of removing. thesilica. reacted. on..the glassfiber. surfaces in accordancewith this invention.

The. reacted silica. which appears to. bemore orless integratediwith. the glassfib er surfaces provides somedegreeoff'protection against mutual: abrasion between fibers, but it is. expedient to: followheat treatment almostimmediately with. a coatingoflubricant or protectant and a curingstep-for. the coatingif indicated.

Treatmentin. accordance with thisinvention is .not re-. stricted.tofabricswovenof continuous glassfibers, but maybeapplied'to staplefibersor continuous glassfibers, or..fabrics.formed.-therefrom.. It may also be-practiced with certain. combinations of glass fibers. with other fibrous materials: capableofwithstanding, the processing temperature, for example, asbestos.

It will be understood that thesolids content of silicain thetreating: composition. may 'beincreased or: decreased beyondcthe. 15 per cent concentration. of Example -1', dc pending upon. theamethodl of: application, .the concentra-. tionwhich .it :is. desired to deposit in theglassfiber surfaces,- .andthe. degree. of. delustering. desired in the: fibers orwfabric. Thus thG SOlldS COHtCHLOf: silica in the treating;v composition may. vary. from l to 30 per cent by weight or more.

Instead ofimpregnation ofthefibers bysubmerging thefabric in..a:bath.of.ther-aqueous suspension, applicationnof the silica-containing composition may. be madeby. a paddr: or by other conventional' process such as flow coating,spraying,.brushing, ,dip squeeze,,and the like.

As pointed out in the example, it is usually convenient .to dry the treatedfabric. or fibers. prior to heattreatment. This enables the desired heattreatment'to'be effectedat a later date, ,and even at a distant station. However, coat ingandheat treatment'may;if desired, be carried'out as a continuous'operationi Air 'di'yingwill 'suifice to-remove the-"diluent from-the treated fabric; bllt'eVflPOlElfiOnDf-flid onto the treated glass diluent may be hastened by exposure to elevated temperatures not to exceed heat treatment temperature for a short time.

Temperatures suitable for heat treatment are capable simultaneously of fiber relaxation and weave setting. Suitable heat treating temperatures range from 400 F. to about 50 below the fusion temperature for the particular glass composition, but it is preferable to carry out heat treatment between 800 and 1250 F.', especially with a borosilicate glass composition. The time of exposure depends primarily on the temperature of heat treatment and it may vary proportionately from 50 or more hours at 400 F. to two to three seconds at 1250 or 1300 F.

Lubrication of the glass fibers after heat treatment with the silica on the surfaces thereof may be effected with a wide variety of materials. It is preferred to lubricate the glass fibers with an organo-silicon compound of the type described in the Biefeld Patent No. 2,392,805 or other silanes or their polymerization products, hereinafter referred to as polysiloxanes The most desirable organo-silicon compounds for lubrication and coating of the treated glass fibers may be selected of the low molecular weight polysiloxanes of fluid consistency or the higher molecular weight polysiloxanes of waxy or resinous character. Representative of suitable polysiloxanes are dimethyl polysiloxane, lauryl methyl polysiloxane, methyl octadecyl polysiloxane, which are fluids ranging from 50 to over 150 centistokes velocity. Suitable organosilicon lubricating materials may also be selected of such copolymers as dimethyl, phenyl, methyl polysiloxanes, or methyl ethyl, phenyl and methyl polysiloxane, which are waxy or resinous members. Silanes which may be used include octadecyl trichlorosilane, didodecyl dichlorosilane, and the like.

Example 2.-A glass fiber fabric treated in accordance with Example 1 may be coated with a composition containing from 1 to 5 per cent of lauryl methyl polysiloxane having a viscosity of 1500 centistokes in solution with toluene. The treated fibers are then heated to a tempera ture of 550 to 650 F. for 20 minutes to set silicon on the glass fiber surfaces. 7

Example 3.--Instead of lauryl methyl polysiloxane, the glass fibers treated in accordance with Example 1 may be dipped in a solvent solution containing from 2 to 10% by weight of didodecyl dichlorosilane, followed by heat treat ment at a temperature of 600 F. for minutes.

Example 4.-A fabric treated in accordance with Example 1 may be immersed in a solvent solution of methyl ethyl phenyl and methyl siloxane resin present in concentrationsranging from 1 to 10% by weight; The fabric, after immersion in the polysiloxane bath, may be passed over squeeze rolls to remove excess therefrom and then baked at a temperature of 750 F. for minutes.

Instead of, or in combination with, the lubrication of the treated glass fibers, protective agents may be applied fiber surfaces by way of a coating resin or the like, selected of materials which are primarily organic in nature, mosetting resinous materials of the type phenol-formal dehyde or other phenol-aldehyde, urea-aldehyde, melamine formaldehyde, poly ester resins, including allyl and vinyl derivatives thereof, and copolymers thereof. Instead, use may be made of thermoplastic materials, with or' without plasticizer such as polystyrene, polyacrylic acid derivatives, including polymethyl methacrylate, ethyl methacrylate, and the like, polyvinyl esters such as polyvinyl acetate, polyvinyl chlorides and copolymers of vinyl acetate and vinyl chloride, cellulose ethers and esters such as cellulose acetate, cellulose trilate, ethyl cellulose, and the like, natural resinssuch as like.

Example 5.A fabric prepared in accordance with Example 1 may be coated with'an aqueous dispersion containing 4 percent by weight polyvinyl acetate; The coat-.

shellac,.gelatin, casein, and the the organosuch, for example, as the there natural and synthetic rubbers, and

. resinous material may plication of 4 ing composition may be applied by means of a padder or by a dip-squeeze process in amounts sufiicient to coat the fibers, or, in the event that a coated fabric is desired, the

be applied in amounts to fill the interstices of the fabric. After apthe resinous coating composition, the coating may be set by heat treatment at a temperature of about 300 to 450 F; for 10 to 30 minutes.

Example 6.A fabric treated in accordance with Example 1 may subsequent to heat treatment be coated with a 3 to 6 percent butadiene-acrylonitrile elastomer in aqueous dispersion. Heat treatment to set the elastomer .on the treated glass fiber surfaces may be carried out at temperatures ranging from 300 to 450 F. for 10 to 20 minutes.

Materials primarily lubricating in character may also be used alone or in combination with the polymeric materials described. These include oils, waxes, cationic, active amine compounds of the type described in the Sloan Patent No. 2,356,542, Werner complex compounds of the type described by Iler in Patent No. 2,273,040, and the like.

Example 7.Instead of polyvinyl acetate, the fabric produced by Example 1 maybe flow coated with a com: position containing 5% water solution of a phenol formaldehyde resin reacted to an intermediate stage of polymeric growth and a 1% dispersion of sulfonated mineral oil. Resinous cure can be achieved by subsequent treatment of the fabric at a temperature of 350 F. for 20 to 30 minutes.

When used in combination with the treated materials previously described as in Examples 2 to 7, such lubricants may be embodied in. amounts ranging from 0.5 to 2% by weight of the treating composition.

In the manufacture of textiles, it is desirable to deposit a relatively low concentration of the coating or of the protective agent on the heat treated glass fiber surfaces. The lower limit of concentration corresponds to an amount sufficient to cover the surfaces with at least a monomolecular film, and may consist of as little as 0.5% by weight of the coated fabric. The upper limit of concentration corresponds to that which will not undesirably stiffen the fibers in the fabric or tend to bind the fibers as an adhesive. Usually the upper limit of concentration is 2% by weight, but up to 10% by weight may be used, especially when the coated material is predominantly lubricating or plasticizing in character. To secure this low concentration in uniform distribution, application is preferably made by conventional means from diluted compositions which may employ organic solvents to effect solution, or water or incompatible liquids to effect emulsion or dispersion.

When coating materials primarily organic in character are applied, best practice calls for a subsequent treatment of the fabric at a temperature below 400 F. for driving olf the diluent and for setting the materialon the treated glass fiber surfaces. When the materials applied are substantially inorganic in character, such as the organo-silicons, to set the material on the glass heating fibers surfaces may be conducted at considerably higher temperatures within the range of 400 to 900 F., but

preferably within the range of 550 to 650 F. By regulating the amount of coating material, the type of coating material, and the degree or extent of heat treatment, the characteristics of the resulting fibers may be varied from silky softness to a starchy ilfness, such as is often desired in draperies, curtains, or other hangings. Heat treatment at the'temperatures described may be con ducted for a period of time ranging from one to thirty minutes or more. r a

As previously pointed out, one of the. important ad vantages of this invention resides in the possibilty of incorporating coloringmaterials in a permanent fashion onto the glass fiber surfaces.

by the usualtechniques for dyeing and printing asemin higher concentrations Coloring may be achieved plo'yed' in the textile'trade'. Suitable dyes include'methyl violet, Victoria blue, malachite green, brilliant green, rhodamine dye and thioflavin'e', or acid dyes of the type nig'rosine dye, or induline'dyes or lake-forming pigments such as the alizarine dyes, lithol'red, Para red, tolirdine red, Hansayellow, Ponsolblue, phthalo'cyanine dye, syan blue, Monastral blue,alizar'inecyclamine, amaranth, and the like. Su'itableinorganic pigments which may be incorporated by aqueous dispersion or in' suitable resinous carriers include cadmium red, chrome yellow, molybdate orange, Paris green, Ultramarine blue, cobalt blue, carbon black, and various coloring metal oxides which will hereinafter be described. This invention also provides for permanentcolori'ngof glass fibeisas an incidence to the fabrication steps; For'example',-coloring oxides-may be incorporated withthe silica in the treating composition'for substantial integration withthe glass fiber surfaces upon heat treatment.

Heat treatment of the type employed in this invention is not'harmful'to the inorganic coloringmetal oxides, but by proper selection of' temperature in the heat treating step, the resulting color'developed can be varied through specific color ranges. For example, nickel oxide incorpo'rated with the silica in'amoun'ts ranging from 5 to 20% by weight thereofwill develop a greenish-blue color responsive'to mild heat treatment on the glass fiber surfaces, while exposure for ten minutes at 600'to 650 F. will-cause a color change to an attractive grayish-yellow h'ue; Iron oxide is also illustrative of a material which may be heat treated to'introduce' various colors. Chromium oxide, which imparts a blue color, and cobalt-oxide, which imparts a pink color whenused'alone incombination with the silica, may be blended together' in various proportions to provide'shades varying from violet to green-blue. Lead oxide gives a deep yellow when blended with antimony oxide. The combination of chromium, iron, and zinc oxide gives colors ranging from yellow-brown to red-brown to maroon. Cadmium provides a yellow color, and copper and chromium'oxide provide a blue-black color. Other shades and complementary colors may also be developed by mixing various metal oxides in desirable proportions.

The following example will illustrate the practice of coloring glass fibers by the introduction of a coloring metal oxide as an ingredient in'combination with the silica for coating the glass fibers, followed by heat treatment to integrate the particles onto the glass fiber surfaces in a manner to provide the described characteristics and also to impart permanent color to the fibrous structure.

Example 8.'A woven fabric of glass fibers is submerged into an aqueous dispersion containing 20% by weight colloidal silica and 4% by weight nickel oxide. The coated fabric is dried and then heat treated at atemperature of about 850 to 950 F. for one to 'three minute's. Heat'treatment iscarried out under oxidizing conditions so as more completely to burn off any size which may previously have been applied to the fiber surfaces and to maintain the metallic components as the corresponding oxide. The resulting fabric has the silica particles apparently strongly bonded to the glass fiber surfaces and the nickel oxide imparts a yellowish-green color over'the entire surface of the fabric. It will be understood that the metal oxides introduced to impart color may be varied in composition and in concentrations within amounts ranging from 2 to about 20% by Weight of the treated composition and that the metal oxides may be applied to the glass fiber surfaces prior to heat treatment in combination with the silica or in a treatment separate and apart therefrom.

An important concept of this invention resides in the development-of a permanent color on'the glass fiber surfaces as an incidence to the thermal reaction for coordinating the silica particles with the glass fiber surfaces. It has been found that certain metallic salts, when reacted on the glassfiber surfaces in combinationwith the silica particles under the conditions -of heat treatment previously describedform acolored reaction product, the color of which depends greatly upon the metallic component of the salt; its concentration,- and the conditions of heat treatment;

ln' p'ractice, it"is preferred to make use of organo'metallic salts'because; under the conditions of heat'treatment, it isbelieved that'th'e organic component-is driven ofi'and that the metallic component remains to form the corresponding coloring oxide or to form a colored reaction product uniformly distributed over the glass fiber surfaces: Suitable"organo'metallie' compounds whichmay be incorporatedin solvent solution or in aqueous dispersion include saltssuch asthe naphthanates, benzoates, acetates, rosinates, resinates; an'd'sal'ts'of other aliphatic, aromatic, and keto-aromatic'acids such as'the formates, propionates, phe'nylates; a'ndthe like; Use may also be made of compounds wherein the'rn'etallic component is to be found in the anionic group, such as the stannates, molybdates; arso'nates, arsonites, chromates, plumbates, and the like. The metallic component of the organo metallic compounds hereina'bove described may be seleeted of a polyvalent metal such as copper, chromium, cobalt; nickel, manganese, lead, arsenic, uranium, iron, bismuth, vanadium; cadmium, silver, selenium, zinc, and the like. Representative salts include cobalt naphthanates, nickel naphthanates, lead rosinates, copper rosin'a-tes; chromium phenylates, zinc acetates, iron naph thanates, cadmium rosinates, and the'like.

()rgano-metallic compounds of the type described'rnay be applied from solvent solutionprior to or subsequent to the application of thesilic'a; or theymay be applied as=a dispersion-in combinatio'ntherewith to form a single treating composition. Solventsfor salts of the-type desc'ri'lfed' inclndeStodda'rd solvent, xylene, toluene, naphtha,-'coal"ta'r' products; petroleum solvents, aromatic solvents, ethers, esters, keto'nes; and the like. Permanent color resultswlie'n' application is made of compositions containing from 012- to 2 0% by weight of the organo metallic compound;

Instead of orga'no' metallic salts and the'like, coloring r'ea'ctionproducts'may also be developed by the use of inorganic metallic sal tsin corresponding concentrations appliedfromsolvent solutions'butpreferably applied in aqueousdispersion in combination With'the silica to form a single treating'composition. Representative of the inorganic metallic salts which may be used are metals of the type previously described as one component in' combination with radicals to form corresponding chlorides, iodides; nitrates; sulfates; chromates, stannates, and the like, such, for example, asferric'chloride,,cupric' chloride, stannic chloride, silver nitrate, chromium chloride, lead chroma'te; and the like. 7

Example 9 Inthe use of color-forming metallic salts in combination with silica in'th'e treatment of glass fibers to develop a' permanent color in a fabric having characteris tics of the type described, a woven fabric of continuous glass fibers is submerged in an aqueous dispersion containing 12% colloidal silicaand 4% ferric chloride. The treated fabriois dried and'then subjected to a heat treatment at a temperature of I 'to- 1200 F. for about five seconds. As a result of this treatment; afabric is-formed having a' brownish-red tinge throughout and characterized by the desirable properties heretofore described as-resulting from the heat treatment of glass fibers' with silica deposited thereon; The colored fabric may be treated with a 4% solution of lauryl methyl polysiloxane as a protective agent, followedby baking at a' temperature ofabout 500 to 650 F. for- 102 O minutes.

Example 1 0.-A- woven fabric of continuous glass fibers-may be'c'oate'd with an aqueous dispersion contain ing 15% colloidal'silica and'3% of a dispersion of nickel naphthanate which has been incorporated as a 70% solutio'n' of nickel naphthana'te'- in Stoddard solvent.- The treated fabrie'is lighf blue in colbr'gbut u on heat treat ment at a temperature of about 950 to 1050 F. for 1 to'2 minutes, a yellowish-green coloration is formed throughout the surface.

The colored fabric having the particles of silica integrated with the surfaces thereof may be lubricated as a continuous operation by immersion in an aqueous medium containing 2% by weight mineral oil followed by baking at a temperature'of about 350 F. for to minutes.

Example 11.Instead of coating the colored fabric produced in accordance with Example 10 with an oil lubricant, the fibers of the fabric may be immersed in a bath containing 4% by weight polyvinylidene chloride in solution, followed by heat treatment at a temperature of 300m 400 F. for 15 minutes.

Glass fibers treated in the manner described to provide an over-all color continue to be highly receptive to other coloring agents such as the'dyes and the pigments previously described, whereby coloring and printing of the fibers or fabric may be carried out by conventional processes well-known in the trade as applied to ordinary textile fabrics formed of cotton, wool, silk, and the like.

7 The ability to print onto a glass fiber fabric or to color a glass fiber fabric by after'treatment in the manner described herein as permitted by fibers treated in accordance with the inventive concepts herein described, provide a marked advance in the application and use of glass fibers in the textile trade and constitutes an important.

phase of this invention.

Coloring materials may, instead of being incorporated with the silica or applied after the silica treatment by the techniques which have heretofore been described, be incorporated as an ingredient with the coating compositions applied to the silica-coated fibers after heat treatment. When incorporated in the coating compositions, such, for example, as in the lubricant or in the organo silicon compounds or in the resinous protective agents, the coloring agents may be compounded therein as in a paint or the like. By limiting the baking temperature of the coated fibers to between 300 to 400 F., ordinary coloring agents such as dyes and pigments may be used. With the organo silicons which are tolerant of considerably higher temperatures, ed therewith may be selected of the more heat-stable coloring agents such as the metal oxides or the metal salts, which can be converted to coloring reactive prodacts at the elevated temperature for baking. Suitable concentrations of the coloring agent in the respective coating compositions may be selected to meet the particular needs, but, ordinarily, concentrations in the range of 2 to 10% by weight of a dye or 2 to by weight of pigment, may be used.

It will be understood that invention herein lies in the silica-treated glass fibers and the method for producing same, as well as in the silica-treated glass fibers having coloring agents, protective agents, and lubricants incorporated therein, and methods for manufacturing same. It will be further understood that changes may be made in the techniques of application and treatment 'without departing from the spirit of the invention, especially as defined in the following claims.

I claim:

1. In the preparation of a glass fiber product, the step of heating glass fibers having a layer of colloidal silica on the surfaces therof for at least 3 seconds to 50 hours varying proportionately with a temperature ranging from 50 F. below the fusion temperature for the particular glass composition to 400 F. V

2. In the prepartion of a glass fiber product, the step of heating glass fibers having a layer of colloidal silica on the surfaces thereof for'3 seconds to 30 minutes at a temperature ranging from 1250 to 800 F.

3. In the preparation of a glass fiber product, the steps of treating the glass fibers having a composition containing from 1 to 30 percentby weight of colloidal silica to the coloring agents incorporat- I deposit silica particles on the surfaces'thereof, and heating the treated fibers for at least 3 seconds to 50 hours proportionately at a temperature ranging from 50 F. below the fusion temperature for the particular glass fiber composition to 400 F.

4. Glass fibers produced by the method of claim 1.

5. In the preparation of a glass fiber product, the steps of heating glass fibers having colloidal silica on the surfaces thereof for at least 3 seconds to 50 hours varying proportionately at a temperature ranging from 50 F. below the fusion temperature for the glass composition of which the fibers are formed to 400 F., and then coloring the glass fibers by the applicationof a coloring material.

6. In the preparation of a glass fiber product, the steps of heating glass fibers having colloidal silica on the surfaces thereof for at least 3 seconds to 50 hours varying proportionately at a temperature ranging from 50 F. below the fusion temperature for the glass composition of which the fibers are formed to 400 F., and then coating the glass fibers with an organic film forming material.

7. The method of treating glass fibers as claimed in claim 6 in which the coating applied to the glass fibers is an organic lubricating composition. 7

8. In the preparation of a glass fiber product, the steps of heating glass fibers having colloidal silica on the surfaces thereof for at least3 seconds to 50 hours varying proportionately with a temperature ranging from 50 F. below the fusion temperature for the glass composition of which the fibers are formed to 400 F., coating the treated glass fibers with an organo-silicon compound, and then baking the coated fibers at elevated temperature to set the organo-silicon compound on the glass fiber surfaces.

9. The method of preparing a glass fiber product as claimed in claim 8 in which the organo-silicon compound is baked on the glass fiber surfaces at a temperature ranging from 400 to 800 F. for from 1 to 180 minutes.

10. In the preparation of colored glass fibers, the steps of heating glass fibers having colloidal silica on the surfaces thereof for at least 3 seconds to 50 hours varying proportionately with a temperature ranging from 50 F. below the fusion temperature for the glass composition of which the fibers are formed to 400 F., and then -coating the glass fibers with an organic film forming material compounded with coloring agent to color the. glass fibers.

11. In the preparation of colored glass fibers, the steps of heating glass fibers having colloidalsilica on the surfaces thereof for at least 3 seconds to 50 hours varying proportionately with a temperature ranging from 50 F. below the fusion temperature for the glass composition 'of which the fibers are formed to 400 F., coating the glass fibers with an organic polymer, and then heating the glass fibers to set the polymer on'the surfaces of the silica treated glass fibers. 7

l2. Treated glass fibers produced by the method of claim 8. V

13. In the preparation of colored glass fibers, the step of heating glass fibers having colloidal silica and finely divided colored metal oxide distributed over thesurfaces thereof at a temperature between 5 0 F. below the fusion temperature for the glass composition of which'the fibers are formed to 400 F. for a time ranging from 3 seconds at the higher temperature to 50 hours at the lower temperature until the silica adheres strongly to the fiber surfaces.

14. Colored claim l3.

15. In the preparation of heating with finely divided colored metal oxide on the surfaces thereof for at least 3 seconds to 50 hours varying proportionately with a temperature ranging the fusion temperature for the glass composition of which the fibers are formed to 400 F.

glass fibers produced by themethod of 16. In the preparation of colored glass fibers, the steps of colored glass fibers, the step glass fibers having colloidal silica in admixture from 50 F. below. 7

of treating glass fibers having a composition containing 1 to 30 percent by weight of an aqueous suspension of finely divided silica and 5 to 20 percent by weight based on the amount of silica of a colored metal oxide in finely divided form to deposit the particles on the surfaces of the glass fibers, and heating the treated fibers for at least 3 seconds to 50 hours proportionately with a temperature ranging from 50 F. below the fusion temperature for the glass composition of which the fibers are formed to 400 F.

17. The method for coloring glass fibers as claimed in claim 15 which includes the additional step of coating the colored glass fibers with a protective organic film forming material.

18. The method for coloring glass fibers as claimed in claim 15 which includes the additional step of coating the colored glass fibers with an organic lubricant.

19. The method for coloring glass fibers as claimed in claim 20 which includes the additional steps of coating the glass fibers with an organo-silicon compound, and baking the coated glass fibers at a temperature ranging from 400 to 800 F. for 1 to 180 minutes to set the organo-silicon compound on the glass fiber surfaces.

20. Colored glass fibers produced by the method of claim 19.

21. In the preparation of a glass fiber product, the steps of treating the glass fibers with an aqueous composition containing from 1 to 33 percent by weight of colloidal silica to deposit a uniform coating of the colloidal silica over the glass fiber surfaces, drying the coating on the glass fiber surfaces and then heating the coated glass fibers to a temperature within the range of F. below the fusion temperature for the glass composition of which the fibers are formed to 400 F. for a time ranging from 3 seconds at the higher temperature to 50 hours at the lower temperature.

References Cited in the file of this patent UNITED STATES PATENTS Re. 19,372 Walton Nov. 13, 1934 2,215,150 Hannen Sept. 17, 1940 2,442,976 Heany June 8, 1948 2,505,629 Thomsen et al Apr. 25, 1950 2,513,268 Steinman June 27, 1950 2,526,684 Powers Oct. 24, 1950 2,577,936 Waggoner Dec. 11, 1951 2,593,817 Waggoner Apr. 22, 1952 2,593,818 Waggoner Apr. 22, 1952 

1. IN THE PREPARATION OF A GLASS FIBER PRODUCT, THE STEP OF HEATING GLASS FIBERS HAVING A LAYER OF COLLOIDAL SILICA ON THE SURFACES THEREOF FOR AT LEAST 3 SECONDS TO 50 HOURS VARYING PROPORTIONATELY WITH A TEMPERATURE RANGING FROM 50* F. BELOW THE FUSION TEMPERATURE FOR THE PARTICULAR GLASS COMPOSITION TO 400* F. 